This invention relates to a stabilizer composition comprising at least one processing stabilizer selected from special phosphite and mono- and diphosphonite compounds, at least one acid scavenger selected from the group consisting of selected metal stearates, hydrotalcites, oxides and hydroxides of alkaline earth metals, at least one UV stabilizer selected from compounds containing at least one 2,2,6,6-tetraalkylpiperidinyl group and, optionally, at least one sterically hindered phenolic antioxidant. The invention relates also to a solid masterbatch composition or a liquid concentrate comprising an above-mentioned stabilizer composition. The invention further relates to a process for stabilizing polymeric materials selected from the group consisting of special polyolefins comprising adding to the polymeric material a stabilizing quantity of said stabilizing composition. The invention also relates to stabilized polymeric material comprising said stabilizer composition and the above-mentioned polymeric material.
The rapid progress in the development of polymerization catalysts, especially supported catalysts and metallocenes, for the manufacture of polyolefins has made a variety of polymers available which differ significantly in their properties from the xe2x80x9cearly generationxe2x80x9d plastics. The problem to maintain these superior properties during processing and service life of the plastic articles has been aggravated especially in polyolefins produced by Generation II to V catalyst systems which are not removed from the polymer after finalizing the polymerization reaction. Even though such catalysts can be deactivated by catalyst poisons, such as steam, aliphatic alcohols, ethers or ketones, their residual activity can still remain to a certain extent. They can attack the polymer and cause premature failures during its end-use; and furthermore, such catalyst residues can also affect the additives which are supposed to safeguard the integrity of plastic materials.
It is well known that several cations with a positive charge xe2x89xa72, especially transition metal ions of the 3d, 4d, and 5d seriesxe2x80x94typical catalysts for olefin polymerizationxe2x80x94, can catalyze the decomposition of phosphites and phosphonites, in particular the hydrolysis of such typical processing stabilizers, finally leading to products with acidic properties and also undesired free phenol. These decomposition products as such can, moreover, cause many disadvantageous secondary effects; for example negative interactions with other additives, especially hindered amine UV stabilizers and phenolic antioxidants, eventually disturbing the entire balance of the additive system contained. In consequence thereof, problems can become apparent already during melt processing of the polymer, e.g. in the form of gel particles, various kinds of deposits or black specks, as well as during its service life, e.g. as reduced mechanical properties, surface cracks or premature embrittlement, when the polymer is exposed to daylight or climate influences.
Many of these undesired processes in a polymeric matrix have been found to originate from a certain acidity, originally present or later formed during the lifetime of a polymer. Therefore, sufficient amounts of acid scavengers, such as metal stearates or oxides, are added to overcome the aforementioned problems. One of the most widely used acid scavengers is calcium stearate, typically used in concentrations of 0.03-0.15%.
However, several other undesired processes, which cannot directly be correlated with the formation of acidity, have been observed in a polymeric matrix despite the presence of acid scavengers. Although the details of such reactions or mechanisms are not fully understood, the consequences thereof can become clearly visible. For instance, certain combinations of plastic additives appear to show negative interactions, often expressed as reduced overall performance, compared with the individual effects of the single additives applied alone in the same polymer.
One example of such negative interactions is the simultaneous use of certain processing stabilizers, e.g. SANDOSTAB P-EPQ or IRGAFOS 12, together with sterically hindered amines (HALS) in UV stabilized polyolefins. Both types of additives are commercially, respectively from a technical viewpoint, important products and essential for the use in high performance plastics. The phosphorus compounds are known to exceptionally safeguard the integrity of the polymer during melt processing; HALS compounds are the state-of-the art stabilizers to protect polyolefins against the detrimental influence of UV light. However, these two types of additives are known to interact antagonistically and, therefore, it has been explicitly recommended not to use any combinations thereof (See publication of Dr. W. O. Drake of Ciba-Geigy, Basel in xe2x80x9cPlastics Newsxe2x80x9d, April 1989, pages 36-45.) In particular, the efficiency of HALS as UV stabilizers is said to be drastically reduced in such cases, limiting the industrial use of such combinations significantly.
It is the objective of the invention to solve the above-mentioned and to provide a high performance stabilizer composition for the stabilization of polyolefins, in particular those which are produced by Generation II to V (or higher) catalyst systems which are not removed from the polymer after the polymerization reaction.
In accordance with the present invention said problem is solved by a stabilizer composition comprising
a) at least one processing stabilizer selected from the group consisting of phosphite, monophosphonite and diphosphonite compounds of formula I or II 
xe2x80x83in which
m is 0 or 1;
n is 0 or 1;
each R10 and each R11, independently, is an aliphatic, alicyclic or aromatic group of 1 to 24 carbon atoms, optionally further substituted (for example by linear or branched aliphatic groups or alkaryl substituents) (hereinafter defined as the monovalent significances of R10 or R11, respectively);
or both groups R10 and/or R11 form a cyclic group with a single phosphorus atom (hereinafter defined as the divalent significances of R10 or R11, respectively);
Y is xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94CH(R15)xe2x80x94 or xe2x80x94C6H4xe2x80x94;
where R15 is hydrogen or C1-6alkyl or COOR6 and R6 is C18alkyl,
b) at least one acid scavenger selected from the group consisting of sodium stearate, magnesium stearate, zinc stearate; magnesium or magnesium/zinc hydrotalcites, optionally coated with 5 to 50% of metal stearate; zinc oxide, zinc hydroxide, calcium oxide, calcium hydroxide, magnesium oxide and magnesium hydroxide,
c) at least one UV stabilizer selected from compounds containing at least one 2,2,6,6-tetraalkylpiperidinyl group and
d) optionally at least one sterically hindered phenolic antioxidant selected from the group consisting of octadecyl-3-(3xe2x80x2,5xe2x80x2-di-tert.-butyl-4xe2x80x2-hydroxyphenyl)propionate, tetrakis[methylene-3-(3xe2x80x25xe2x80x2-di-tert.-butyl-4xe2x80x2-hydroxyphenyl)propionate]methane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert.-butyl-4-hydroxyphenyl)benzene, 1,3,5-tris(3,5-di-tert.-butyl-4-hydroxyphenyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)trione and tris[3,5-di-tert.-butyl-4-hydroxybenzyl]isocyanurate.
According to the invention, there is provided a synergistic additive package, i.e. a stabilizer composition for polyolefins, in which highly effective processing stabilizers and hindered amine UV stabilizers are combined without sacrificing the individual effects of the additives contained. The selected acid scavengers are able to compensate the negative interactions of processing stabilizers and HALS compounds. In some cases, even superior efficiency of the HALS compounds has been observed, compared with analogous formulations containing such processing stabilizers, which do not show such negative interactions.
Preferably, in component a) the monovalent significances of R10 and R11 are independently linear, branched or cyclic C1-24aliphatic groups; or aromatic groups, e.g. phenyl, preferably substituted 1 to 5-fold with C1-12alkyl or aralkyl groups, as for example with R10=R11=2,4-di-tert.-butylphenyl.
It will be apparent that when both groups R10 and/or both groups R11 form a cyclic group with a single phosphorus atom, each such cyclic group comprises the respective moiety xe2x80x94Oxe2x80x94Pxe2x80x94Oxe2x80x94 to which both groups R10 or both groups R11 are attached.
When component a) is at least one compound of formula I, it preferably comprises at least 55%, more preferably at least 70%, by weight, of total compound(s) of formula I.
When component b) is magnesium hydrotalcite or magnesium/zinc hydrotalcite coated with a metal stearate, the amount of metal stearate is preferably 7 to 48%, by weight, based on the weight of the magnesium hydrotalcite or magnesium/zinc hydrotalcite.
The weight ratio of component a) to b) in the stabilizer composition according to the invention is preferably 3:1 to 1:7, more preferably 2:1 to 1:2.
The typical ratios of components a) to d), when the latter is present, are 1:5 to 5:1, preferably in the range of 1:3 to 3:1. The amount of component c), relative to the sum of components a) plus b) plus d), may vary from 1:100 to 100:1, preferably, however, from 1:20 to 20:1.
The synergistic additive package comprising the components a), b), c) and optionally d) is preferably used in the polymers at concentrations of 0.05 to 2%, more preferably 0.1 to 1%, based on the weight of the polymer.
Component a) is preferably a mixture of
i) 50-80% of a diphosphonite of formula (x) 
ii) 5-25% of a monophosphonite of formula (y) 
iii) 5-25% of a phosphite of formula (c) 
in which each of R10 is 2,4-di-tertiary butylphenyl; and where the percentages are weight percentages based on the sum of the compounds of formulae (x), (y) and (z) being 100%.
Preferably, such a mixture of compounds constitutes at least 80%, more preferably at least 85%, most preferably at least 90%, by weight, of component a).
Typically, component i) comprises three isomers of formula (x) in which the phosphorus atoms are attached to the biphenylene moiety at the 4,4xe2x80x2-, 4,3xe2x80x2- and 3,3xe2x80x2-positions, said isomers being present, respectively, in amounts of 36-46%, 17-23% and 2-5%, by weight, respectively, based on the total composition of component a).
More preferably, component a) is the product of condensing 4 mols of 2,4-di-tert.-butylphenol per mol of the product of the Friedel-Crafts reaction of 2 mols of phosphorus trichloride per mol of biphenyl, as described, for instance, in U.S. Pat. No. 4,075,163, the disclosure of which, particularly column 1, line 13 to column 4, line 9 and Example 12, is incorporated herein by reference. More particularly, it is a product composed of
i) 60-65 parts of the diphosphonite of formula 1x 
(tetrakis(2,4-di-tert.butylphenyl)biphenylene diphosphonite)
ii) 10-15 parts of the monophosphonite of formula 1(y) 
(bis(2,4-di-tert.butylphenyl)biphenylene monophosphonite)
iii) 10-15 parts of the phosphite of formula 1z 
(tris(2,4-di-tert.butylphenyl)phosphite);
iv) up to 3.5 parts of 2,4-di-tert.butylphenol;
v) up to 1% of inorganic chloride;
vi) up to 0.5% of volatile matters; and
vii) up to 5% of the compound of the formula 
This mixture of components i)-vii) is commercially available as SANDOSTAB P-EPQ from CLARIANT International Ltd., Switzerland.
In the foregoing description of SANDOSTAB P-EPQ parts and percentages are by weight based on 100 parts, by weight, of total components i)-vii).
In component a) the compound of formula II, chemically characterized as 2,2xe2x80x2,2xe2x80x3-nitrilo[triethyl-tris(3,3xe2x80x2,5,5xe2x80x2-tetra-tert.butyl-1,1xe2x80x2-biphenyl-2,2xe2x80x2-diyl)phosphite], can be applied as obtained by the procedure given in Example 4 of U.S. Pat. No. 4,318,845 or Example 4 of U.S. Pat. No. 4,374,219, with a melting point of 121-134xc2x0 C., or in its amorphous solid form with a melting range of 105-110xc2x0 C. according to U.S. Pat. No. 5,276,076, or in its triclinic beta-modification with a melting range of 200-207xc2x0 C. according to U.S. Pat. No. 5,326,802, or in its gamma-modification with a melting range of 178-185xc2x0 C. according to U.S. Pat. No. 5,331,031, or in its monoclinic alpha-modification with a melting range of 145-165xc2x0 C. according to U.S. Pat. No. 5,334,739, in mixtures, melts or in solutions thereof. The disclosures of the aforementioned patents are incorporated herein by reference.
Preferably the divalent significances of R10 and R11 are. e.g. 
where each R14, independently, is selected from C1-22alkyl or C7-22aralkyl and p=0 to 4, preferably 1 to 3.
The 2,2,6,6-tetraalkylpiperidinyl group of component c) is of formula q or qxe2x80x2, preferably formula q 
in which
R is hydrogen; oxygen; xe2x80x94OH; C1-24alkyl; xe2x80x94Oxe2x80x94C1-24alkyl; xe2x80x94Oxe2x80x94COxe2x80x94C1-24alkyl; xe2x80x94Oxe2x80x94CO-phenyl phenyl-O-phenyl or xe2x80x94COR5; where R5 is xe2x80x94C(R3)xe2x95x90CH2, C1-6alkyl, phenyl, xe2x80x94COxe2x80x94C1-24alkyl, xe2x80x94CO-phenyl, xe2x80x94NR7R8, xe2x80x94CH2xe2x80x94C6H5, xe2x80x94COxe2x80x94OC1-12alkyl, or xe2x80x94COOH; R3 is hydrogen or C1-4alkyl; R7 is hydrogen, C1-12alkyl, C5-6cycloalkyl, phenyl, phenyl-C1-4alkyl or C1-12alkylphenyl and R8 is C1-12alkyl or hydrogen,
each R1, independently, is xe2x80x94CH3 or xe2x80x94CH2(C1-4alkyl) or both groups R1 form a group xe2x80x94(CH2)5xe2x80x94 and
each R2, independently, is xe2x80x94CH3 or xe2x80x94CH2(C1-4alkyl) or both groups R2 form a group xe2x80x94(CH2)5xe2x80x94.
Preferably, R is hydrogen; oxygen; xe2x80x94OH; C1-24alkyl; xe2x80x94Oxe2x80x94C1-24alkyl; xe2x80x94Oxe2x80x94COxe2x80x94C1-24alkyl; Oxe2x80x94CO-phenyl or xe2x80x94COR5.
Such groups of formula q) and qxe2x80x2) are known as the effective group in numerous hindered amine light stabilizers (HALS).
More preferably, component c) is a compound containing a group of formula qxe2x80x3
where Rxe2x80x2is hydrogen, oxygen, OH, C1-12alkyl, xe2x80x94Oxe2x80x94C1-12alkyl, xe2x80x94COxe2x80x94C1-8alkyl, phenyl or xe2x80x94O-phenyl, preferably hydrogen, oxygen, C1-12alkyl, xe2x80x94Oxe2x80x94C1-12alkyl or xe2x80x94COxe2x80x94C1-8alkyl.
Preferably, component c) is selected from HALS 1 to HALS 18 below 
where R21 is C12-14alkyl (e.g. a mixture of C12H25 and C14H29); 
where R21 is as definded above 
in which in HALS 1 to HALS 18
R is Rxe2x80x2 where Rxe2x80x2 is as defined above and
nxe2x80x2 is a number from 3 to 20.
Most preferably, component c) is selected from
Bis(2,2,6,6-tetramethyl-4piperidyl)sebacate;
Bis(1,2,2,6,6-pentamethyl-4piperidinyl)(3,5-ditert.butyl-4-hydroxybenzyl)butylpropane dioate;
Bis(1,2,2,6,6-pentamethyl-4piperidinyl)sebacate;
8-Acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro(4,5)decane-2,4-dione;
Butanedioic acid, bis(2,2,6,6-tetramethyl-4-piperidinyl)ester;
Tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butane tetracarboxylate;
(2,2,6,6-tetramethyl-4-piperidyl)/xcex2,xcex2,xcex2xe2x80x2,xcex2xe2x80x2-tetramethyl-3,9-(2,4,8,10-tetraoxaspiro(5xe2x80x2,5)undecane)diethyl)-1,2,3,4-butane tetra carboxylate;
7-oxa-3,20-diazadispiro(5.1.11.2)heneicosan-20-propanoic acid, 2,2,4,4-tetramethyl-21-oxo, dodecylester (xe2x80x9cHostavinxe2x80x9d N 24);
Octadecene-(N-(2,2,6,6-tetramethylpiperidinyl-4)-N-maleinimido-oxalic acid diamide co-polymer;
N-(2,2,6,6-tetramethyl-4-piperidinyl)-Nxe2x80x2-amino-oxamide;
OO-t-amyl-O-(1,2,2,6,6-pentamethyl-4-piperidinyl)monoperoxicarbonate;
xcex2-Alanine-N-(2,2,6,6-tetramethyl-4-piperidinyl)-dodecylester;
Ethanediamide,N-(1-acetyl-2,2,6,6-tetramethylpiperidinyl)-Nxe2x80x2-dodecyl;
3-dodecyl-1-(2,2,6,6-tetramethyl-4-piperidinyl)-pyrrolidin-2,5-dione;
3-dodecyl-1-(1,2,2,6,6-pentamethyl-4-piperidinyl)-pyrrolidin-2,5dione;
3-dodecyl-1-(1-acetyl,2,2,6,6-tetramethyl-4-piperidinyl)-pyrrolidin-2,5-dione;
(xe2x80x9cSanduvor(copyright)xe2x80x9d 3058)
4-benzoyloxy-2,2,6,6-tetramethylpiperidine;
1-[2-(3,5-di-tert.butyl-4-hydroxyphenylpropionyloxy)ethyl]-4-(3,5-ditert.butyl-4-hydroxy-phenyl-propionyloxy)-2,2,6,6-tetramethyl piperidine;
2-methyl-2-(2xe2x80x3,2xe2x80x3,6xe2x80x3,6xe2x80x3-tetramethyl-4xe2x80x3-piperidinylamino)-N-(2xe2x80x2,2xe2x80x2,6xe2x80x2,6xe2x80x2-tetra-methyl-4xe2x80x2-piperidinyl)propionylamide;
1,2-bis(3,3,5,5-tetramethyl-2-oxo-piperazinyl)ethane-1-isopropyl-3,3,5,5-tetramethyl-2-piperazinone
Tetrakis(2,2,6,6-tetramethyl-4-piperidyl)1,2,3,4-butane tetracarboxylate; 4-oleoyloxy-2,2,6,6-tetramethylpiperidine;
Poly-[(6-morpholino-s-triazin-2,4diyl)[(2,2,6,6-tetramethyl-4-piperidinyl)imino]-hexamethylene-[(2,2,6,6-tetramethyl-4-piperidinyl)imino)];
Poly-[6-[1,1,3,3-tetramethyl-butyl)imino]-s-triazin-2,4-diyl)[2-(2,2,6,6-tetramethyl-4-piperidinyl)imino]hexamethylene-[4-(2,2,6,6-tetramethyl-4-piperidinyl)imino)];
1,3,5-triazine-2,4,6-triamine-Nxe2x80x2,Nxe2x80x3-[ethanediyl-bis[[[4,6-bis[butyl(1,2,2,6,6-pentamethyl-4-piperidinyl)amine]-1,3,5triazin-2-yl]imino]propane-diyl]]bis[Nxe2x80x2,Nxe2x80x3-dibutyl-Nxe2x80x2,Nxe2x80x3-bis-(1,2,2,6,6-pentamethyl-4-piperidinyl)];
Butanedioic acid, polymer with 4-hydroxy-2,2,6,6-tetramethyl-1-piperidine-ethanol; 2,2,4,4-tetramethyl-7-oxa-3,20-diaza-dispiro[5.1.11.2]heneicosan-21-one;
Bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidinyl)sebacate;
Poly(methylpropyl-3-oxy-[2,2,6,6-tetramethyl-4-piperidinyl]-siloxane);
1,3,5,7,9,11-hexaaza-4,10-dione-tricyclo[12.1.1.013,14]-tetradecane-1,7-bis(2,2,6,6-tetramethyl-4-piperidinyl).
Especially useful as component c) are
Bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate;
Bis(1,2,2,6,6-pentamethyl-4-piperidinyl)sebacate;
Butanedioic acid, bis(2,2,6,6-tetramethyl-4-piperidinyl)ester;
Poly-[(6-morpholino-s-triazin-2,4-diyl)[(2,2,6,6-tetramethyl-4-piperidinyl)imino]-hexamethylene-[(2,2,6,6-tetramethyl-4-piperidinyl)imino)];
Poly-[6-[1,1,3,3-tetramethyl-butyl)imino]-s-triazin-2,4-diyl)[2-(2,2,6,6-tetramethyl-4-piperidinyl)imino]hexamethylene-[4-(2,2,6,6-tetramethyl-4-piperidinyl)imino)];
1,3,5-triazine-2,4,6-triamine-Nxe2x80x2,Nxe2x80x3-[ethanediyl-bis[[[4,6-bis[butyl(1,2,2,6,6-pentamethyl-4-piperidinyl)amine]-1,3,5-triazin-2-yl]imino]propane-diyl]]bis[Nxe2x80x2,Nxe2x80x3-dibutyl-Nxe2x80x2,Nxe2x80x3-bis-(1,2,2,6,6-pentamethyl-4-piperidinyl)];
Butanedioic acid, polymer with 4-hydroxy-2,2,6,6-tetramethyl-1-piperidine-ethanol;
Bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidinyl)sebacate;
Poly(methylpropyl-3oxy-[2,2,6,6-tetramethyl-4-piperidinyl]-siloxane)
Further, component c) can optionally be combined with known UV absorbers.
Components a) to c) and optionally d) of the stabilizer composition according to the invention can be added individually to the polymeric materials to be stabilized or can be blended to form an additive package, prior to the addition to the polymeric material. This additive package can be prepared by mixing the components a) to c) and optionally d) in an appropriate mixer to obtain a powder blend which preferably is compacted to non-dusting granules by known methods. Another possibility to prepare such additive packages is to prepare a homogeneous melt of the components a) to c) and optionally d) at elevated temperatures which is then cooled and pelletized by known methods.
Further additives that can be employed along with a stabilizer composition according to the invention include antioxidants as well as UV absorbers (e.g. 2-(2xe2x80x2-hydroxyphenyl)-benztriazoles, 2-hydroxybenzophenones, 1,3-bis-(2xe2x80x2-hydroxybenzoyl)benzene, salicylates, cinnamates and oxalic acid diamides; UV quenchers such as benzoates and substituted benzoates, antistatic agents, flameproofing agents, lubricants, plasticisers, nucleating agents, metal deactivators, biocides, impact modifiers, fillers, pigments and fungicides.
Further according to the invention there is provided a solid masterbatch composition or liquid concentrate for use as a stabilizer in polymeric materials. Said masterbatch composition comprises 10 to 80% by weight, preferably 15 to 40% by weight of a stabilizer composition according to the invention and 90 to 20% by weight, preferably 85 to 60% by weight, of a polymeric material which is identical or compatible with the polymeric material to be stabilized.
The liquid concentrate comprises 10 to 80% by weight of a stabilizer composition according to the invention and 90 to 20% by weight of a solvent. By xe2x80x9csolventxe2x80x9d is meant here a liquid in which all or part of the stabilizer composition may be dissolved.
A further subject matter of the invention is a process for stabilizing polymeric materials comprising adding to the polymeric material a stabilizing quantity of the stabilizer composition or of the solid masterbatch or of the liquid concentrate according to the invention. This stabilizing quantity is, as aforementioned, related to the polymeric materials to be stabilized, independent of the selected addition technique.
The stabilizing composition or the masterbatch composition according to the invention may be incorporated by known methods into the polymeric material to be stabilized. Of particular importance is the dry-blending with the polymeric material or coating shaped polymer particles, e.g. polymer spheres, with the present compositions in the form of a liquid, a solution or a suspension/dispersion.
Of particular importance is the blending of the stabilizing composition or the masterbatch composition according to the invention with the polymeric material to be stabilized in the melt, for example in a melt blender or during the formation of shaped articles, including films, tubes, fibers, and foams by extrusion, injection molding, blow molding, spinning or wire coating.
The polymeric material to be stabilized according to the invention is selected from the group consisting of homopolyolefins and copolyolefins produced in the presence of a so called Generation II or higher catalyst (not subjected to a catalyst removal step after the polymerization process), and mixtures and blends thereof with other polymers.
Preferably, the polyolefin is selected from the group consisting of homopolypropylene, copolypropylene, homopolyethylene, copolyethylene and mixtures or blends thereof or with other polymers.
Said poly- and coplyolefins are especially prepared using processing catalysts known as Generation II to Generation V catalysts and which have not been subjected to a catalyst removal step. By the term xe2x80x9ccatalyst removal stepxe2x80x9d used herein is meant a step for the purpose of positively removing the catalyst residues contained in the polymerized polyolefins or treating the polyolefins with the compound which can react with the catalyst residue and inactivate or solubilize the residue, such as alcohols or water, and then removing the inactivated or solubilized catalyst residue by physical means such as filtration, washing and centrifuging. The step of adding a small amount of catalyst poisons such as ethers, alcohols, ketones, esters and water to the resulting polymer, to inactivate the catalyst remaining after completion of the polymerization does not fall under the above-mentioned definition of the xe2x80x9ccatalyst removal stepxe2x80x9d.
What is meant by Generation I catalysts are titanium halide catalysts in combination with an organo aluminum compound, such as an organo aluminum halide.
What is meant by Generation II catalysts are Generation I catalysts supported on an organo magnesium compound or catalysts based on an organo chromium compound, such as dicyclopentadienyl chromium complex, supported on SiO2.
What is meant by Generation III catalyst is a Zeigler type complex catalyst supported on a halogen containing magnesium compound.
What is meant by a Generation IV catalyst is a generation III catalyst with a silane donor.
What is meant by a Generation V catalyst is either a bis-indenyl organo titanium compound supported on alumoxane or a bis cyclopentadienyl titanium halide activated by an aluminum alkyl compound.
Further generations of highly specific catalysts, which are presently under development and which are especially useful for manufacturing highly stereoregular poly-alpha-olefins, belong to the higher generations of supported catalyst systems. Examples for the microstructure of such highly stereoregular polyolefins are syndiotactic polypropylene, isotactic stereoblock polymers, isotactic polypropylene containing steric defects randomly distributed along the polymer chain (so called anisotactic polypropylene) or stereorregular stereoblock polymers. Reviews of the most recent developments in the field of metallocene based catalyst systems are: W. N. Riss and H. Ledwinka: Kunstoffe 83 (1993) 8, pages 577-583; R. Muelhaupt: Nachr. Chem. Tech. Labs 41 (1993) 12, pages 1341-1351; R. Leaversuch: Modem Plastics, October 1991, pages 46-49 and W. Spaleck: Hoechst High Chem Magazine 14 (1993), pages 44-48. Due to the rapid progress in the development of newer generation catalyst systems, the commercial significance of these polymers with novel, highly interesting properties is increasing.
These generations of catalysts are also described in the Twelfth Annual International Conference on Advances in the Stabilization and Controlled Degradation of Polymers held in Luzern, Switzerland, May 21-23, 1990 in an article on pages 181-196 inclusive by Rolf Muelhaupt entitled xe2x80x9cNew Trends in Polyolefin Catalysts and Influence on Polymer Stabilityxe2x80x9d The contents of this article are incorporated by reference, especially Table I on page 184 describing the Generation of Catalysts.
The invention also relates to a stabilized polymeric material comprising
a) a stabilizing composition according to the invention and
b) a polymeric material selected from the group consisting of homopolyolefins and copolyolefins, preferably selected from the group consisting of homopolypropylene, copolypropylene, homopolyethylene and copolyethylene, produced in the presence of a so called Generation II or higher catalyst and mixtures or blends thereof or with other polymers.
Further, in this specification, where a range is given, the figures defining the range are included therein. Any group capable of being linear or branched is linear or branched unless indicated to the contrary.
For the avoidance of doubt, in the specification t.butyl means tertiary butyl (xe2x80x94C(CH3)3).
The invention will now be illustrated by the following Examples in which all parts and percentages are by weight unless indicated to the contrary.